The invention is based on a brake booster as defined hereinafter.
Brake boosters, includes multi-circuit brake boosters, such as shown by (German Offenlegungsschriften Nos. 25 31 264 and 31 51 292). These known brake boosters may be embodied such that one brake circuit is closed and the other brake circuit is generally an open brake circuit. The open brake circuit is acted upon directly by a reservoir pressure, which is derived from a pressure supply means and directed to the brake circuit via a control valve or brake valve. If the pressure supply means fails, the open brake circuit becomes a closed brake circuit. Generally the open brake circuit includes an annular piston, which is mounted on a pedal tappet actuated by the brake pedal. A need exists for brake boosters which are combined with an anti-skid or anti-lock system (ABS) and included in the ABS concept in such a way that as an integrated component they can also be used, at least indirectly, for ABS functions. In this way, while maintaining acceptable anti-skid system performance, it is possible to attain a combined brake booster and anti-skid system at considerably reduced cost, in terms of both materials and engineering expense.